The objectives of this project are to compare ligand-surface receptor and cytoplasmic events in normal and abnormal lymphocytes. This will be done for two reasons: first, to use the abnormalities uncovered in malignant cells to understand normal lymphocyte function; second, to possibly define properties of the malignant cell that are related to malignant behavior. The events to be studied are: 1) redistribution of surface molecules after binding of ligands; 2) the contractile events that accompany redistribution; 3) the loss of surface molecules after binding; 4) the synthesis and reexpression of new surface elements; 5) the changes in cell motility that take place after binding. Normal human blood and splenic lymphocytes will be compared to malignant (lymphoma and lymphocytic leukemia) lymphocytes as well as some lymphocyte cell lines. Methods to be used include fluorescent antibodies to detect surface molecules, the fluorescence-activated cell sorter to quantitate fluorescence, biochemical and immunochemical techniques to evaluate contractile mechanisms and synthesis of surface molecules, and assays of cellular motility including migration of lymphocytes through microporous filters. The following kinds of changes will be sought in abnormal lymphocytes: changes in membrane lipid viscosity; changes in distribution of molecules on the surface; abnormalities in the synthesis of surface molecules and their insertion into the membrane; abnormalities of transmembrane attachment of surface molecules; and abnormalities of the submembrane cellular contractile system. When such defects are found, they will be examined in detail on a molecular level. The emphasis will be on the full and careful study of selected kinds of abnormal lymphocytes that are the most likely to yield information about normal functions and malignant behavior.